Alternator and Battery problem

  mercedes/c-class/2001-2007

I want to replace the alternator in my C200K sport coupe, Mercedes Benz (model 2001) I don't know whether is socket or bolt type, inorder not to a wrong one.
2, What type of battery can I buy,I have made findings on Otral Battery ,is it a good choice?

Thanks for your quick response,
Ofe

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